Hetch Hetchy Water and Power reported Apr 29, 2016 as follows:

A number of events will impact Tuolumne River flows in the next couple weeks. We will be making releases from Hetch Hetchy, including a high flow pulse during the week of 5/8. Lake Eleanor will likely fill and begin spilling, resulting in increased flows in Eleanor Creek. Finally, generation at Holm Powerhouse (Cherry Creek) will begin to vary from the April pattern beginning May 1. Detailed explanations of these are below, followed by a table summarizing our estimates of flow volumes.

1) Hetch Hetchy releases: Since April 17, we have had increased releases from Hetch Hetchy Reservoir at ~1000 cfs and we plan on continuing at ~1000 cfs for another week, until May 8. Starting May 8, we will increase releases for a pulse flow. May 8 through May 10 we will ramp up to a maximum release of ~6500 cfs, which we will hold for 2 days. After the pulse, we will ramp back down to 1000-2000 cfs over the next 4-5 days. Details on scheduled flows are in the table below.

2) Lake Eleanor filling and spilling: Lake Eleanor has been rising as spring runoff brings water from snowmelt downhill. We anticipate Lake Eleanor to fill and begin spilling in the next 2 weeks, depending on weather. Current inflows have peaked at 1000 cfs. The Cherry / Eleanor tunnel has been and will continue to transfer 200-400 cfs from Eleanor to Cherry. We anticipate peak spill at Eleanor to be in the 700-1000 cfs range.

3) Generation change at Holm Powerhouse: For the past month we have scheduled near maximum generation (~950 cfs) at Holm Powerhouse in most hours. We are currently planning to have a reduction in Holm powerhouse draft beginning May 1. The “general” pattern is as follows:

a. Weekdays: ~350-450 cfs 10 PM to 6 AM, 450-550 cfs 9AM to 4PM, 600-700 cfs all other hours

b. Weekends: ~350-450 cfs 9PM to 4PM, 600-700 cfs 4PM to 9PM.

Please note that this is a tentative plan and may vary depending on conditions. Changes to this plan change will be posted here.

Schedule of Hetchy Releases – Note that these do not include natural flows outside of our facilities (such as the South and Middle Forks of the Tuolumne, Granite Creek, etc…):

All flows in cfs	Hetchy Release	Spill at Kirkwood	Holm Draft	Eleanor and Cherry Release	Eleanor^4 Spill	Total Releases
4/29 to 5/7	1000	700-800	350-700	10	0-100	2060-2610
5/8^1	1000-2200	700-800	350-700	10	100-200	2160-3910
5/9^1	2200-4100	700-800	350-700	10	100-250	3360-5860
5/10^1	4100-6500	700-800	350-700	10	100-300	5260-8310
5/11	6500	700-800	350-700	10	100-350	7660-8360
5/12^2	4800-6500	700-800	350-700	10	100-400	5960-8410
5/13^2	3600-4800	700-800	350-700	10	100-500	4760-6810
5/14^2	2700-3600	700-800	350-700	10	100-600	3860-6810
5/15^2	2000-2700	700-800	350-700	10	100-600	3160-4810
5/16^2	1700-2000	700-800	350-700	10	100-600	2860-4110
5/17 – 5/24^3	1700	700-800	350-700	10	200-1000	2960-3490

¹ Hetchy releases will be increasing through the day during this period

² Hetchy releases will be decreasing through the day during this period

³ End date of 1700 cfs releases will depend on weather and reservoir conditions.

⁴ Eleanor spill timing and volume is an estimate. Weather conditions can change this greatly.

The normal caveats apply – all generation and release schedules rely on weather and reservoir conditions, and unit availability.

Any significant changes to the schedule will be posted on the bulletin board.